Problem: Stay at standby LED after power on. Later found output relay poor contact, sound distorted or cutoff.
Cause: Output transistor one shorted. Negative rail fuse open.
Actions:
- Replace one transistors 2SA1386 by 2SA1186 (closest found).
- Service relay to ensure good contact (R < 0.1 ohm).
- Recap some e-caps on main board.
- Replace bias adjust VR to 10 turn 500ohm, one VR shorted.
- Rusty frame is painted with silver pen.
- Touch up some suspect cold solder joints.
- Retune all Bias for L/R channels.
- Test for output power and distortion.
